This is an application to fund a competitive renewal for the PI's ongoing prospective study Initiation and Progression through Early Drinking Milestones in Underage Drinkers (R01 AA016838). The aims under the initial funding cycle, which focused on the period of early-to-mid adolescence, were to identify milestones demarcating drinking stages (e.g., first full drink, heavy drinking) and to examine the extent to which risk factors explain variability in initiation and progression through milestones. Participans in the base study were enrolled in middle school (N=1,023) and assessed over a 3-year period using a combination of intensive (monthly) web-based assessments of narrow focus complemented by semi-annual assessments with broader content. To date, the study has an incredibly rich assessment of nonspecific and alcohol-related risk factors as well as early alcohol involvement. Sample retention is exceptionally high, with outstanding response rates. The purpose of this renewal study is to continue to assess this valuable cohort through the high school years, a time during which the majority of youth progress through stages marked by increasing involvement with alcohol ranging from any use to early manifestation of the alcohol dependence syndrome. It is also a time during which youth undergo important developmental transitions such as puberty and attainment of a driver's license. In this funding period, we directly shift from a multi-wave, cohort-sequential foundational design to a developmentally driven design that places participants on the same schedule with quarterly assessments through 12th grade (or equivalent). By study end, each participant will provide between 15 and 29 quarterly waves spanning the 6th- 12th grade years. Web-based surveys will continue to assess drinking milestones as well as an array of individual-level and contextual risk factors. In additio, the renewal study will leverage a rich assessment of drinking precursors that provide the scaffolding that support early drinking experiences and help to determine its trajectory. These drinking precursors, which include alcohol-related cognitions and willingness to drink, change as individuals gain familiarity with alcohol either indirectly through exposure to alcohol-related norms (including alcohol references in entertainment media and social networking) or directly, through personal experience with alcohol. The renewal study also assesses important developmental transitions and developmental outcomes relevant to late adolescence. Having a full spectrum of data on alcohol involvement across the full span of adolescence provides an unparalleled opportunity to explicitly compare youth with early versus late onset and to evaluate whether risk factors for initiation to differ from risk factors for other transitions along the dimension of alcohol involvement. The fine grained data collected are critical for illuminating within- person change, not only with regard to outcomes and risk factors, but also for timing as an important moderator of these associations. Findings will inform prevention efforts by identifying modifiable stage-specific risk factors for progression, maintenance, and desistence of drinking in underage youth.